Motorcycle Shock Absorbers
The simple story about shock absorbers is that they absorb or dissipate energy from the surface (pavement, gravel, dirt, etc.,) to keep the tires on the road and give the motorcycle rider a smoother experience.
Hydraulic shock absorbers used on the rear suspensions of motorcycles are similar to those used in cars: They use internal fluid to control up/down motion. The flow of the fluid through internal holes inside the shocks serves to slow down and control rapid movement in the springs as they react to surface irregularities. However, MOTORCYCLE SHOCKS
Motorcycles with only one shock absorber are designated as “monoshock” bikes. Monoshock motorcycles have been the norm since the 1980s, when their performance was developed and proven to be superior to twin shock motorcycles. The term “twinshock” is now used to categorize vintage motorcycles.
If your bike uses two rear shocks, you are probably very aware that the pre-load and damping on both shocks needs to be set the same, otherwise you would experience dangerous handling and braking characteristics.
Pre-Load Adjustment
The pre-load on a rear shock is typically adjusted via a threaded or notched collar on the shock. As the collar is rotated, the coil-over spring is compressed more or less. The more the spring is compressed, the higher the pre-load, and vice versa.
Some shocks, known as air-assist shocks, allow adjustment of preload by changing the air pressure inside the shock. A valve on the shock allows air to be introduced or released from the shock. More air pressure gives more preload, and vice versa.
Damping Adjustment
As alluded to above, damping uses fluid to decrease, or control, the up/down movement of your shock. There’s two types of damping adjustments:
1) REBOUND DAMPING
Controls how fast that spring returns to full length after being compressed. Without rebound damping as part of your shock, the rear of your motorcycle would bounce up and down uncontrollably. (This kind of motion is better saved for amusement park rides, or for those times when you wish to get around on a pogo stick).
2) COMPRESSION DAMPING
Controls the speed the shock is compressed. Too much compression, or too little, for a given rider’s weight, speed, and type of surface, will reduce the traction and handling characteristics of your bike.
All of the suspension adjustments offer myriad ways to tune a motorcycle to a given rider and circumstance. For most riders, finding an acceptable compromise is desired. For racers, their suspension is tuned to each track.
Stock shocks may not offer a separate damping adjustment, but may have a single adjustment for both compression and rebound damping together. This adjustment is usually made by a dial at the very top or very bottom of the shock. The dial selects one of a few different internal hole sizes for the damping fluid flow path. The larger the hole, the less the damping, and vice versa.
